[venus]

> the health effects of flavorings are still out there

This is very true. I have been very concerned with "vapers" I know buying cheap juices from China - to me this is rolling the dice, almost as bad as smoking!

You will find that reputable juice mixers will generally make statements about their ingredients. My usual favourite (indigo vapours - I have no commercial interest, just a customer) for example explicitly state that they do not use any flavour containing diacetyl, acetyl propionyl or acetoin.

Flavours which may contain aldehyde elements are a concern, but what is much more my concern with e-cigs is the long-term effect of propolene glycol inhalation, and potentially significant formaldehyde levels potentially produced by the heating and/or oxidation of the base liquids. There's a decent amount of research ongoing in these areas.

Despite these issues I am reasonably confident that e-cigarettes are within a safety range I am comfortable with if (and only if) used with high-quality liquids.

[thelogos]

I wasn't even aware of the formaldehyde issue. Here I thought propylene glycol is much safer than vegetable glycerin because of the acrolein.

[venus]

Here is the study: http://tobaccocontrol.bmj.com/content/early/2013/03/05/tobac...

Here is a (rather editorialised) summary: http://tobaccoanalysis.blogspot.com.au/2013/03/new-study-of-...

The study found variations up to 20x in levels of formaldehyde contained in the vapour produced by some top e-cigarette products. At the low range, the levels are of little concern and barely above background. At the high range, they are of some concern. Unfortunately brands, etc are not broken down.

I have a strong suspicion that formaldehyde levels correlate with country of origin and/or quality of the liquids involved. If you stick to using PG sourced from countries with reliable certification systems I think it is OK.